Composite materials and process

ABSTRACT

Composite films and film laminates comprising at least one elastomeric core and a surrounding nonelastomeric matrix preferably prepared by coextrusion. The film when stretched and allowed to recover will create an elastomeric composite.

This application is a continuation-in-part of application Ser. No.08/651,807, filed May 21, 1996, which is a divisional of applicationSer. No. 08/427,424, filed Apr. 24, 1995, now U.S. Pat. No. 5,620,780.

BACKGROUND AND FIELD OF THE INVENTION

The invention concerns elastic composites and structures obtainablethereby.

Elastomeric materials have been long and extensively used in garments,both disposable and reusable. Conventionally, the elastic is stretchedand in this stretched condition attached to a substrate. Afterattachment, the elastic is allowed to relax which will generally causethe substrate to shirr or gather. Elastic was at one time applied bysewing, see, e.g., U.S. Pat. Nos. 3,616,770 (Blyther et al.); 2,509,674(Cohen); and 22,038. More recently, this procedure has been displaced bythe use of adhesive, e.g., U.S. Pat. No. 3,860,003 (Buell). Buellproposed the use of an elastic strand in the leg areas of the disposablediaper. Welding has also been proposed in U.S. Pat. No. 3,560,292(Butter) although sonic welding is preferred. A pivotal problem with allthese attachment methods has been how to keep the elastic in a stretchedcondition while applying it to the substrate. A solution has beenproposed in the use of heat shrink elastomeric materials, e.g., U.S.Pat. No. 3,639,917 (Althouse).

In diapers, for example, elastomeric bands are typically used in thewaistband portions such as discussed in U.S. Pat. Nos. 4,681,580(Reising et al.) and 4,710,189 (Lash). Both these patents describe theuse of elastomeric materials which have a heat stable and a heatunstable form. The heat unstable form is created by stretching thematerial when heated around its crystalline or second phase transitiontemperature followed by a rapid quenching to freeze in the heat unstableextended form. The heat unstable elastomeric film can then be applied tothe, e.g., diaper and then heated to its heat stable elastomeric form.This will then result in a desirable shirring or gathering of thewaistband of the diaper. A problem with these materials, other thancost, is the fact that the temperature at which the material must beheated to release the heat unstable form is an inherent and essentiallyunalterable property of the material to be used. This inflexibility cancause problems. First, it is more difficult to engineer the othermaterials with which the waistband is associated so that they arecompatible with the temperature to which the elastomeric member must beheated in order to release the heat unstable form. Frequently thistemperature is rather high which can potentially cause significantproblems with the adhesive used to attach the elastomeric waistband, or,e.g., the protective back sheet or top sheet of the diaper. Further,once chosen the elastomer choice can constrain the manufacturing processrendering it inflexible to lot variations, market availability and costsof raw materials (particularly elastomer(s)), customer demands, etc.

A problem noted with the application of elastic to a diaper, as proposedin U.S. Pat. No. 3,860,003, resides in the proposed use of a singlerelatively large denier elastomeric ribbon. This ribbon will concentratethe elastomeric force in a relatively narrow line. This allegedly causedthe elastic to pinch and irritate the baby's skin. Proposed solutions tothis problem included the use of wider bands of elastic as per U.S. Pat.Nos. 4,352,355 (Mesek et al.) and 4,324,245 (Mesek et al.). Allegedly,this allows the contractive forces to be distributed over a wider areaand prevents irritation of the baby's skin. The preferred elastomerproposed in these applications are films of A-B-A block copolymers witha thickness of 0.5 to 5 mils. Problems noted with these films are thatthey are difficult to handle and must be applied with relativelycomplicated stretch applicators as per U.S. Pat. Nos. 4,239,578 (Gore);4,309,236 (Teed); 4,261,782 (Teed); and 4,371,417 (Frick et al.).

An alternative solution to the pinching problem of U.S. Pat. No.3,860,003 is proposed in the use of multiple strands of relatively smalldenier elastic, as per U.S. Pat. No. 4,626,305 (Suzuki et al), whodescribes the use of three to 45 fine rubber strings to elasticize adiaper. However, to keep the bands properly aligned they are preferablyfused together. The alleged advantage in this method is that a smallnumber of narrow elastic bands can be stretched at a high ratio to givethe same tensile stress that a single equivalent diameter elastic bandwould yield at a lower stretch ratio. Accordingly, the stress can bedistributed over a wider area and less elastic needs to be used (i.e.,as the elastic is stretched more when applied). A similar approach isproposed by U.S. Pat. No. 4,642,819 (Ales et al.). However, Ales et al.uses larger denier elastic bands which act as backup elastic seals foreach other when or if the diaper is distorted during use. A variation ofthis approach is proposed in U.S. Pat. No. 4,300,562 (Pieniak). Pieniakuses a series of interconnected elastomeric strands, in a reticulateform. Wider strands are positioned to engage the narrow portion of atapered surface. This allegedly results in a more even distribution ofstress over where the reticulate elastic engages the tapered surface.Although the use of multiple strands of elastic materials hasadvantages, they are more difficult to incorporate into a garment in aspaced coordinated fashion. Thin elastic strands have a tendency towander and further present a thin profile making adhesion to the garmentsubstrate difficult.

Spaced elastic elements are provided other than by multiple elasticstrands. For example, it has been proposed to provide regionalizedelastic in the waistband portion of a disposable diaper in U.S. Pat. No.4,381,781 (Sciaraffin).

Regionalized elastic is also placed in diaper adhesive fastening tabs asper U.S. Pat. Nos. 4,389,212 (Tritsch); 3,800,796 (Jacob); 4,643,729(Laplanche); 4,778,701 (Pape) and 4,834,820 (Kondo et al.). Thesepatents are directed to different composite structures designed to yielda fastening tab with an elasticized central portion and inelastic orrelatively rigid end portions for attachment to either side of a garmentclosure. These composites are quite complicated and generally are formedby adhering several separate elements together to provide theelasticized central region.

Elastomers used in these structures also exhibit relatively inflexiblestress/strain characteristics which cannot be chosen independently ofthe activation temperature. Materials with a high modulus of elasticityare uncomfortable for the wearer. Problems with a relatively stiff orhigh modulus of elasticity material can be exaggerated by thecoefficient of friction and necking of the elastomer which can cause thematerial to bite or grab the wearer.

In U.S. Pat. No. 5,501,679, there is disclosed a multi-layer elasticlaminate having at least one elastomeric layer and at least onecoextensive skin layer which addresses certain of the above notedproblems in the art. In addition, the laminate has extremely useful andnovel properties. When cast, or after formation, the elastic laminate issubstantially inelastic. Elasticity can be imparted to the inelasticform of the laminate by stretching the laminate, by at least a minimumactivation stretch ratio, wherein an elastic laminate material will formimmediately, over time or upon the application of heat. The method bywhich the elastic laminate material is formed can be controlled by avariety of means. After the laminate has been converted to anelastomeric material, there is formed a novel texture in the skinlayer(s) that provides significant advantages to the laminate. Despitethe numerous advantages in the materials of the copending application,there is room for improvement for some applications such as thosediscussed above. For example, where intermittent elasticized regions aredesired such as in a diaper fastening tab or where it is desirable tohave discrete adjacent longitudinal bands of elastic. In theseapplications, laminated plastic films are less desirable. For example,they must be assembled into complex composite structures as discussedabove to provide regionalized elastic. Therefore, it is desirable toretain the advantages of the material disclosed in the copendingapplication while providing structures having regionalized elastic areasor elastic bands which can be simply constructed and are also moreresistant to delamination than multi-layer laminate structures.

SUMMARY OF THE INVENTION

The present invention relates to improved non-tacky, nonelastic materialcapable of becoming an elastic film when stretched, which film materialis laminated to a fibrous web before or after being stretched. Thefibrous web is bonded at least to nonelastic regions of the elasticfilm. The film material is comprised both of an elastomeric polymericcore region, which provides the elastomeric properties to the elasticfilm material in elastic regions and a polymeric matrix, which iscapable of becoming microtextured at specified areas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(a) through (i) are cross-sectional segments of extruded laminatesof the invention before microstructuring.

FIG. 2 is a schematic representation of a modified combining adapterused to form the invention material.

FIG. 3 is a schematic representation of a process and apparatus used tocoextrude the laminates of the invention.

FIG. 4 is a schematic representation of the microstructure formed in theelastomeric regions of the invention film material that has beenuniaxially stretched.

FIG. 5 is a schematic representation of a tape tab formed of theinvention film material.

FIG. 6 is a scanning electron micrograph (100x) of a film material thathas been uniaxially stretched transverse to the extruder machinedirection.

FIG. 7 is a scanning electron micrograph (100x) of the film material ofFIG. 5 uniaxially stretched in the machine direction showing periodicmacrostructure folding.

FIG. 8 is a scanning electron micrograph (1000x) of a film materialuniaxially stretched in the machine direction showing periodicmacrostructure folding.

FIG. 9 is a cutaway top view of a tape tab cut from a roll of theinvention film material.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention relates to novel non-tacky laminates of a nonwovenfabric to an elastic film having nonelasticized or nonelastic regionsand elastic regions. The elastic film is formed of a nonelastic filmmaterial capable of becoming elastic when stretched comprising at leastone elastomeric core region surrounded by a relatively nonelastomericmatrix. Selected regions containing the elastomeric core regions arestretched beyond the elastic limit of the surrounding matrix material.The deformed matrix is then relaxed with the elastomeric core forming anelastic region.

The softness of the elastic film, and strength in the elastic regions isadvantageously increased by laminating a fibrous web to the film. Thislamination is enhanced by nonelasticized regions 7, which do not form amicrostructure thereby enhancing adhesion between the elastic film andthe fibrous web or the like, also forming a suitable surface for coatingan adhesive or attaching a mechanical fastener element. In theelastomeric core 2 containing region(s), a fibrous web laminated to theelastic film can also limit extensibility of the elastomeric core 2containing regions. Preferably, the fibrous web is a nonwoven web suchas a consolidated or bonded carded web, a meltblown web, a spunbond web,a spunlace web or the like. The fibrous web is preferably bonded orlaminated to the film by adhesives, thermobonding, ultrasonic welding orthe like when at least the nonelastic regions 7 are substantially flat,e.g., prior to stretching or while stretching the film, for longitudinaland transverse stretching, where the elastic activated portions orregions of the film laminate can further be non-necking. The fibrous webcan also be attached after stretching and recovering the film fortransverse stretched webs. Alternatively, the film can be directlyextruded onto one or two fibrous webs. The fibrous web must beextensible when attached to the film prior to stretching the film andpreferably the fibrous web will not fully recover when stretched withthe film such that the fibrous web will form pleats in the elasticregion when the elastic region recovers.

Transverse stretched nonwoven film laminates are particularlyadvantageous in that they will be substantially flat and elastic in onedirection and nonextensible, under typical tensioning forces used indiaper and like web assembly production lines, in the oppositedirection. This makes these laminates particularly advantageous where asoft one directional elastic is needed, such as a training pant sidepanel. Longitudinally stretched nonwoven film laminates are lessdesirable in these uses in that they are not flat, have less resistanceto extensibility in the nonelastic direction and cannot be handledeasily by longitudinally unwinding from a roll.

The term microstructure means that the matrix skin layer contains peakand valley irregularities or folds which are large enough to beperceived by the unaided human eye as causing increased opacity over theopacity of the laminate before microstructuring, and whichirregularities are small enough to be perceived as smooth or soft tohuman skin. Magnification of the irregularities is usually required tosee the details of the microstructured texture.

Typical constructions of the film material 1 are shown in FIG. 1(a)through (i) where 2 designates the elastomeric core and 3 the matrixmaterial. FIG. 1 is an edge view of the material as it is formed,preferably by a coextrusion process. Matrix skin layers 4 and 5 inconjunction with the thickness of the core material 6 determines theperformance of the material, e.g., the shrink mechanism, themicrostructure, etc. The nonelastomer containing matrix region or field7 will not recover when stretched except by gathering into periodicfolds between parallel recovering elastic core containing regions.

The elastomer can broadly include any material which is capable of beingformed into thin films and exhibits elastomeric properties at ambientconditions. Elastomeric means that the material will substantiallyresume its original shape after being stretched. Further, preferably,the elastomer will sustain only small permanent set followingdeformation and relaxation which set is preferably less than 20 percentand more preferably less than 10 percent of the original length atmoderate elongation, e.g., about 400 to 500 percent. Generally, anyelastomer is acceptable which is capable of being stretched to a degreethat will cause permanent deformation in a relatively inelastic skinlayer of the matrix material over the elastomer. This can be as low as50 percent elongation. Preferably, however, the elastomer is capable ofundergoing up to 300 to 1200 percent elongation at room temperature, andmost preferably up to 600 to 800 percent elongation at room temperature.The elastomer can be both pure elastomers and blends with an elastomericphase or content that will still exhibit substantial elastomericproperties at room temperature.

As discussed above, heat-shrinkable elastics have received considerableattention due to the ability to fabricate a product using the unstablestretched elastomer at ambient conditions and then later applying heatto shirr the product. Although these elastomers are contemplated for usein the present invention, other non-heat-shrinkable elastomers can beused while retaining the advantages of heat shrinkability with the addeddimension of the possibility of substantially controlling the heatshrink process. Non-heat-shrinkable means that the elastomer, whenstretched, will substantially recover sustaining only a small permanentset as discussed above. The elastomeric core(s) can be formed from blockcopolymers which are elastomeric such as those known to those skilled inthe art as A-B or A-B-A block copolymers. These block copolymers aredescribed, for example, in U.S. Pat. Nos. 3,265,765; 3,562,356;3,700,633; 4,116,917; and 4,156,673, the substance of which areincorporated herein by reference. Styrene/isoprene, butadiene orethylenebutylene/styrene (SIS, SBS or SEBS) block copolymers areparticularly useful. Other useful elastomeric compositions can includeelastomeric polyurethanes, ethylene copolymers such as ethylene vinylacetates, ethylene/propylene copolymer elastomers orethylene/propylene/diene terpolymer elastomers. Blends of theseelastomers with each other or with modifying non-elastomers are alsocontemplated. For example, up to 50 weight percent, but preferably lessthan 30 weight percent, of polymers can be added as stiffening aids,such as polyvinylstyrenes, polystyrenes such aspoly(alpha-methyl)styrene, polyesters, epoxies, polyolefins, e.g.,polyethylene or certain ethylene/vinyl acetates, preferably those ofhigher molecular weight, or coumarone-indene resin. The ability to usethese types of elastomers and blends provides the invention filmmaterial with significant flexibility.

Viscosity reducing polymers and plasticizers can also be blended withthe elastomers such as low molecular weight polyethylene andpolypropylene polymers and copolymers, or tackifying resins such asWingtack™, aliphatic hydrocarbon tackifiers available from GoodyearChemical Company. Tackifiers can also be used to increase theadhesiveness of an elastomeric core(s) to the matrix material. Examplesof tackifiers include aliphatic or aromatic liquid tackifiers, aliphatichydrocarbon resins, polyterpene resin tackifiers, and hydrogenatedtackifying resins. Aliphatic hydrocarbon resins are preferred. Additivessuch as dyes, pigments, antioxidants, antistatic agents, bonding aids,antiblocking agents, slip agents, heat stabilizers, photostabilizers,foaming agents, glass bubbles, starch and metal salts for degradabilityor microfibers can also be used in the elastomeric core layer(s).Suitable antistatic aids include ethoxylated amines or quaternary aminessuch as those described, for example, in U.S. Pat. No. 4,386,125(Shiraki), who also describes suitable antiblocking agents, slip agentsand lubricants. Softening agents, tackifiers or lubricants aredescribed, for example, in U.S. Pat. No. 4,813,947 (Korpman) and includecoumarone-indene resins, terpene resins, hydrocarbon resins and thelike. These agents can also function as viscosity reducing aids.Conventional heat stabilizers include organic phosphates, trihydroxybutyrophenone or zinc salts of alkyl dithiocarbonate. Suitableantioxidants include hindered phenolic compounds and amines possiblywith thiodipropionic acid or aromatic phosphates or tertiary butylcresol, see also U.S. Pat. No. 4,476,180 (Wnuk) for suitable additivesand percentages.

Short fibers or microfibers can be used to reinforce the elastomericcore(s) for certain applications. These fibers are well known andinclude polymeric fibers, mineral wool, glass fibers, carbon fibers,silicate fibers and the like. Further, certain particles can be used,including carbon and pigments.

Glass bubbles or foaming agents are used to lower the density of theelastomeric layer and can be used to reduce cost by decreasing theelastomer content. These agents can also be used to increase the bulk ofthe elastomer. Suitable glass bubbles are described in U.S. Pat. Nos.4,767,726 and 3,365,315. Foaming agents used to generate bubbles in theelastomer include azodicarbonamides. Fillers can also be used to someextent to reduce costs. Fillers, which can also function as antiblockingagents, include titanium dioxide and calcium carbonate.

The matrix can be formed of any semi-crystalline or amorphous polymerthat is less elastic than the core(s) and will undergo permanentdeformation at the stretch percentage that the elastomeric core(s) willundergo. Therefore, slightly elastic compounds, such as some olefinicelastomers, e.g., ethylene-propylene elastomers orethylene-propylene-diene terpolymer elastomers or ethylenic copolymers,e.g., ethylene vinyl acetate, can be used as matrix materials, eitheralone or in blends. However, the matrix is generally a polyolefin suchas polyethylene, polypropylene, polybutylene or apolyethylene-polypropylene copolymer, but may also be wholly or partlypolyamide such as nylon, polyester such as polyethylene terephthalate,polyvinylidene fluoride, polyacrylate such as poly(methyl methacrylate)(only in blends) and the like, and blends thereof. The matrix materialcan be influenced by the type of elastomer selected. If the elastomericcore is in direct contact with the matrix the matrix should havesufficient adhesion to the elastomeric core(s) such that it will notreadily delaminate. Where a high modulus elastomeric core(s) is usedwith a softer polymer matrix, a microtextured surface may not form.

Additives useful in the matrix include, but are not limited to, mineraloil extenders, antistatic agents, pigments, dyes, antiblocking agents,provided in amounts less than about 15 percent, starch and metal saltsfor degradability and stabilizers such as those described for theelastomeric core(s).

Other layers may be added between the core(s) and the matrix such as tielayers to improve bonding, if needed. Tie layers can be formed of, orcompounded with, typical compounds for this use including maleicanhydride modified elastomers, ethyl vinyl acetates and olefins,polyacrylic imides, butyl acrylates, peroxides such as peroxypolymers,e.g., peroxyolefins, silanes, e.g., epoxysilanes, reactive polystyrenes,chlorinated polyethylene, acrylic acid modified polyolefins and ethylvinyl acetates with acetate and anhydride functional groups and thelike, which can also be used in blends or as compatiblizers in one ormore of the matrix or core(s). Tie layers are sometimes useful when thebonding force between the matrix and core is low, although the intimatecontact between skin and matrix should counteract any tendency todelaminate. This is often the case with a polyethylene matrix as its lowsurface tension resists adhesion.

The shrink recovery mechanism of the film can be controlled by theconditions of film formation, the nature of the elastomeric core(s), thenature of the skin(s), the manner and direction in which the film isstretched and the relative thicknesses of the elastomeric core and thematrix skin layer(s) over the core(s). By controlling these variables,in accordance with the teaching of this invention, the film material canbe designed to instantaneously recover, recover over time or recoverupon heat activation.

A film material capable of instantaneous shrink recovery is one in whichthe stretched elastomeric material will recover more than 15 percent (ofthe total recovery available) in 1 second. A film capable of time shrinkis one where the 15 percent recovery point takes place more than 1second, preferably more than 5 seconds, most preferably more than 20seconds after stretch, and a film capable of heat shrink is where lessthan 15 percent shrink recovery occurs to the laminate in the first 20seconds after stretch. Percent recovery of the elastomeric corecontaining region is the percent that the amount of shrinkage is of thestretched length minus the original length of the elastomeric corecontaining region. For heat shrink materials, there will be anactivation temperature which will initiate significant heat activatedrecovery. The activation temperature used for heat shrink recovery willgenerally be the temperature that will yield 50 percent of the totalpossible recovery (T_(a-50)) and preferably this temperature is definedas the temperature which will yield 90 percent (T_(a-90)) of the totalpossible recovery. Total possible recovery includes the amount ofpreactivation shrinkage.

Generally, where the matrix skin layers 4 and 5 over the core(s) in thepreferential activation region are on average relatively thin, the filmmaterial will tend to contract or recover immediately after stretched.When the matrix skin thickness 4 and 5 is increased sufficiently, thefilm material can become heat shrinkable in the activated regions. Thisphenomenon can occur even when the elastomeric core(s) is formed from anon-heat shrinkable material. By careful selection of the thicknesses ofthe elastomeric core 2 and the matrix skin layer(s) 4 and 5, thetemperature at which the material recovers by a set amount can becontrolled within a set range. This is termed skin controlled recovery,where generally by altering the thickness or composition of the matrixskins 4 and 5 (assuming a constant matrix width in the noncorecontaining region for longitudinal activation), one can raise theelastic recovery activation temperature of an elastomeric core 2 by asignificant degree, generally more than at least 10° F. (5.6° C.) andpreferably by 15° F. (8.3° C.) and more. Although any matrix skinthickness which is effective can be employed, too thick a matrix skin 4and 5 will cause the material to remain permanently set when stretched.Generally where an average single matrix skin is less than 30 percent ofthe film in this region, this will not occur although more complexretraction can be expected where the elastomeric core aspect ratio issmall (e.g., a round core as per FIG. 1(a)). For most heat or timeshrink materials, the stretched and activated regions of the filmmaterial must be cooled so that the energy released during stretchingdoes not cause immediate heat activated elastic recovery. Fine tuning ofthe shrink recovery mechanism can be accomplished by adjusting thedegree to which the activated regions are stretched. The more stretch,the more the film will tend to instantaneously recover.

Additives to the core discussed above can significantly affect theshrink recovery mechanism. For example, stiffening aids such aspolystyrene can shift an otherwise heat shrinkable material into a timeor instant shrink material. However, the addition of polypropylene orlinear low density polyethylene (less than 15 percent) to astyrene/isoprene/styrene block copolymer core resulted in exactly theopposite effect, namely transforming time or instant shrink materials toheat shrink or no shrink materials. However, the possibility ofpolyolefin use in the elastomeric core is significant from a processingstandpoint in permitting limited recycling of off batches and polyolefinadditives can lower extruder torque.

The overall structure of the present film material may be formed by anyconvenient matrix forming process such as by pressing materialstogether, coextruding or the like, but coextrusion is the presentlypreferred process for forming a material with elastomeric cores within arelatively nonelastomeric material matrix. Coextrusion per se is knownand is described, for example, in U.S. Pat. Nos. 3,557,265 (Chisholm etal); 3,479,425 (Leferre et al.); and 3,485,912 (Schrenk et al). Tubularcoextrusion or double bubble extrusion is also possible for certainapplications. The core and matrix are typically coextruded through aspecialized die and feedblock that will bring the diverse materials intocontact while forming the material.

The composite film materials shown in FIG. 1 can be formed, for example,by the apparatus described in Schrenk et al. Schrenk et al. employs asingle main orifice and polymer passageway die. In the main passageway,which would carry the matrix material, is a nested second housing havinga second passageway. The second passageway would have one or moreoutlets, each defining an elastomeric core, which discharges matrixmaterial flowstreams into the main passageway matrix flow region. Thiscomposite flow then exits the orifice of the main passageway.

Another advantageous coextrusion process is possible with a modifiedmultilayer, e.g., a three-layer, die or combining adapters such as madeby Cloeren Co., Orange, Tex. Combining adapters are described in U.S.Pat. No. 4,152,387 (Cloeren) discussed above. Streams of thermoplasticmaterials flowing out of extruders, or from a specialized multilayerfeedblock, at different viscosities are separately introduced into thedie or adapter, and the several layers exiting the flow restrictionchannels converge into a melt laminate. A suitably modified Cloeren™type adapter 10 is shown in FIG. 2(a) and (b). Three separate polymerflow streams, 11, 12 and 13 are separated and regulated by veins 15 and16. Streams 11 and 13 are of the matrix polymer (which in this case maybe different polymers) while stream 12 is the elastomeric core polymericmaterial. Flow 12 is intercepted by insert 14 with cutouts 17, which canbe the same or different size, which permits passage of elastomericmaterials. The insert is generally attached to one vane and snugglyengaged with the second to allow the vanes to rotate in unison. Thisallows adjustment of the core material position within the matrix.Streams 11, 13 and the flow from stream 12 through cutouts 17 convergeand form the invention film material (a five layer combining adapter isalso useable to incorporate tie layers in the matrix). The combiningadapter is used in conjunction with extruders, optionally in combinationwith multilayer feedblocks, supplying the thermoplastic materials. Sucha scheme for producing the present invention film material is shownschematically in FIG. 3, for a three layer adapter, to form basicmaterials such as those shown in FIG. 1. AA, BB, and CC are extruders.AA', BB' and CC' are streams of thermoplastic material flowing into thefeedblock or manifold die. D is the 3 or more (e.g., 5-layer) layerfeedblock. E is the die and/or combining adapter, F is a heated castingroll, and G and H are rolls to facilitate take-off and roll-up of thefilm material.

The die and feedblock used are typically heated to facilitate polymerflow and layer adhesion. The temperature of the die depends upon thepolymers employed and the subsequent treatment steps, if any. Generallythe temperature of the die is not critical but temperatures aregenerally in the range of 350° to 550° F. (176.7° to 287.8° C.) with thepolymers exemplified.

The regionally elasticizable film material formed will have longitudinalbands of elastomeric material in a matrix of relatively nonelastomericmaterial. When this structure is stretched a microstructured surfacewill form in the matrix skin regions 4 and 5 of FIG. 1. This is shown inFIGS. 6 and 7 for transverse (to the machine direction) and longitudinalstretching and relaxing, respectively. Regions or fields 7 between theelastomeric cores 2, when the film is stretched longitudinally (i.e., inthe machine direction), will gather into folds, as shown in FIGS. 7 and8 for two different films. These folds will be several orders ofmagnitude larger than the microtexture on skin regions 4 and 5. This canadd significant amounts of volume to the elastic film, a desirablequality for use in garments and for certain protective packaging. Thelongitudinally stretched matrix material will also contribute to therecovery mechanism of the film so stretched.

The fold structure in regions 7 will depend on the spacing betweenadjacent elastomeric bands 2 and the degree to which the film isstretched and recovered, as seen in FIGS. 7 and 8 above. Foldssuperimposed on a microstructured surface is possible with structuressuch as 1(b), (h) and (i) where multiple or irregular elastic corescould lead to differing levels of recovery across the film. Theseembodiments would yield differing microstructures across the filmsurface as well as folds in lower recovery areas between areas of higherrecovery.

When the film material is stretched transversely to the elastomeric corebands (i.e., in the cross direction), the material will stretch in theregions containing the elastomeric cores 2 and possibly innonelasticized regions 7. However, region 7 should generally yield afterthe elasticized regions, due to the general lower modulus of theelastomeric material 2, as per FIG. 6. However, if regions 7 have asignificantly lower caliper than the elastomer containing regions, dueto die swell and flow characteristics, region 7 may yield with or priorto the elastomeric core containing regions. When nonelastomer containingregions 7 stretch, they will not recover, therefore increasing thedistance between the elastomeric bands, which will recover in thedirection of stretch as discussed elsewhere. Activation can also bepreferential in areas having higher elastomer content. For example, inFIG. 1(h) the film would tend to elongate preferentially in regionswhere there is an overlap in elastomeric cores.

FIG. 4 is a schematic diagram of the common microstructure dimensionswhich are variable for uniaxially stretched and recovered films in theactivated regions. The general texture is a series of regular repeatingfolds. These variables are the total height A--A', the peak-to-peakdistance B--B', and the peak-to-valley distance C--C'.

Multiaxially stretching may be desirable where a more complexmicrostructure is desired. Biaxially, e.g., stretching creates uniquesurfaces while creating a film which will stretch in a multitude ofdirections and retain its soft feel.

It has also been found that the fold period of the microstructuredsurface is dependent on the core/skin ratio. This is, again, anotherindication of the control possible by careful choice of the parametersof the present invention.

When the film is stretched first in one direction and then in a crossdirection, the folds formed on the first stretch become buckled foldsand can appear worm-like in character with interspersed cross folds.Other textures are also possible to provide various folded or wrinkledvariations of the basic regular fold. When the film is stretched in bothdirections at the same time, the texture appears as folds with lengthdirections that are random. Using any of the above methods ofstretching, the surface structure is also dependent, as stated before,upon the materials used, the thickness of the layers, the ratio of thelayer thicknesses and the stretch ratio. For example, the extrudedmulti-layer film can be stretched uniaxially, sequentially biaxially, orsimultaneously biaxially, with each method giving a unique surfacetexture and distinct elastomeric properties.

The degree of microtexturing of elastic laminates can also be describedin terms of increase in skin surface area. Where the film shows heavytextures, the surface area will increase significantly. Generally, themicrotexturing will increase the surface area by at least 50 percent,preferably by at least 100 percent and most preferably by at least 250percent. The increase in surface area directly contributes to theoverall texture and feel of the film surface.

With certain constructions, the underlying elastomer may tend to degradeover time. This tendency may particularly occur with A-B-A blockcopolymers. Residual stress created during the stretching and recoverysteps of activating the material to its elastomeric form can acceleratethis process significantly. For those constructions prone to suchdegradation, a brief relaxing or annealing following activation may bedesirable. The annealing would generally be above the glass transitionpoint temperature (T_(g)) of the elastomer, above the B block T_(g) forA-B-A block copolymers, but below the skin polymer melting point. Alower annealing temperature is generally sufficient. The annealing willgenerally be for longer than 0.1 seconds, depending on the annealingtemperature. With commercial A-B-A block copolymers (e.g., Kraton™ 1107)an annealing or relaxing temperature of about 75° C. is found to besufficient.

The elastic film laminate can be extensively used in disposable diapers,for example as a waistband located in either the front or side portionsof the diaper at waist level, as leg elastic or in adjustable slip-ondiapers, where the elastic film laminate could be used as, or in, sidepanels around the hip that have zones of elasticity to create a tightfitting garment. The film laminates can be applied as continuous orintermittent lengths by conventional methods. When applied, a particularadvantage of the elastic film laminate is the ability to use thin zonesof elastomers with high stretch ratios while activation of the elasticfilm can occur at a controlled stretch ratio (particularly whenstretching transverse to the elastic band longitudinal direction),depending on the size of the elastomeric core containing regions, theiractivation stretch ratio and modulus behavior.

When used to provide intermittent zones of elasticity the film laminateformed by, e.g., coextrusion can be cut laterally into strips containingportions of one or more elastomeric cores or bands. The elasticcontaining region(s) will be spaced by proper choice of the widths ofnonelastic regions 7 and elastomeric core(s) 6. The elastic portion ofthe film laminate can thus be placed at the proper location to beelasticized in the finished article, see e.g., U.S. Pat. No. 4,381,781(diaper waistbands). The elastic film laminate could also be properlyplaced for diaper legbands, e.g., in a diaper "backsheet". Theelastomeric cores 2 would be coextruded at locations proper forelasticizing the leg regions with liquid impermeable thermoplastictherebetween forming the diaper backsheet.

Another use for the invention film laminate, would be as an elasticizeddiaper fastening tab as per, e.g., U.S. Pat. No. 3,800,796, and shown inFIG. 5. The one or more (not shown) elastomeric core(s) 2 , e.g., couldbe placed at the desired location while providing nonelastic endportions 7. The elasticized film laminate is preferably 10 to 50 mm widefor most conventional tape tab constructions. This provides adequatetension without having to stretch the tape too far onto the diaperfront. This tab could be cut from film stock containing one or moreelastomeric bands 2. Adhesive 8 or a mechanical fastener (e.g., hook orloop) element could then be applied to one or more faces of thenonelastic end portions 7. However, the pressure-sensitive adhesivecoated (or mechanical fastener containing, not shown) end portion 27 forreleasable attaching to the diaper front portion could be 8 to 15 mmwide while the end portion 29 permanently attached to the diaper side iswidened substantially, as shown in FIG. 9 and disclosed in U.S. Pat. No.5,399,219.

In the form shown in FIG. 9, the tabs are cut from a continuous filmlaminate roll of stock material with one or more elastomeric bands 22.The two ends, 27 and 29, are inelastic and preferable both coated with apressure-sensitive adhesive 28. The tab form shown in FIG. 9 wouldresult in no waste (end portion 27 is an inverted mirror image of endportion 29), however, other shapes or tab designs are possible whereinelastic end portion 29 may or may not be adhesive coated. In theembodiment of FIG. 9, the elastics forces are distributed to a wide areaalong the diaper side where end 29 is attached, which results in a morestable securement and better fit resulting from wider distribution ofthe elastic forces along the side portion of the diaper. Generally forthe embodiment of FIG. 9 and like tab forms, the terminal portion of end29 is at least twice as wide as the terminal portion of end 27 with agradual tapering in the elastic region therebetween.

An additional advantage with forming fastening tabs of the inventionelastic film laminate, is the versatility available. The tabs could besold unstretched and easily activated by the customer, alternatively thetab could be applied stretched and activated, in both cases the tackyrubber will not be exposed. An additional advantage with a stretched andactivated film tab is that the activated regions will have a surfacemicrostructure which will tend to release adhesive tape at lowerapplication pressures. This feature can be used to form tabs with adesirable, centrally located, mechanical low adhesion backsize region,which is desirable for fastening tabs such as those disclosed in U.S.Pat. No. 4,177,812 (Brown et al.).

Garments often are shirred to give a snug fit. This shirring can beeasily obtained by applying heat shrink film materials while in anunstable stretched condition and then affecting the shirr by applicationof heat. The elastic film laminate material(s) can be adhered to thegarment by ultrasonic welding, heat sealing and adhesives byconventional methods. Adherence would be preferably in the regions 7.

The counter-balancing of the elastic modulus of the elastomeric core andthe deformation resistance of the matrix material also modifies thestress-strain characteristics of the activated regions of the filmmaterial. The modulus therefore can be modified to provide greaterwearer comfort when the film material is used in a garment. For example,a relatively constant stress-strain curve can be achieved. Thisrelatively constant stress-strain curve can also be designed to exhibita sharp increase in modulus at a predetermined stretch percent. Thenon-activated or non-stretched film as such is easier to handle and muchbetter suited to high speed production processes than would be aconventional elastic.

The composite elastic film laminate is also extremely well suited foruse as a tape backing providing a high loft elastic tape with excellentoxidation resistance, tearability, self-adhesiveness andrepositionability to flat surfaces. The increased tearability isadvantageous in applications where each elastic strand is appliedseparately to a substrate such as a garment. In such garmentapplications, the tape can be readily torn between the elasticstrand-containing regions, particularly when oriented in thelongitudinal direction (i.e., parallel to the elastic strands). Theelastic strands would be easily handled prior to separation and couldthen be applied as separate elastic strands by known methods.

The following Examples are provided to illustrate presently contemplatedpreferred embodiments and the best mode for practicing the invention,but are not intended to be limiting thereof.

EXAMPLE 1

A continuous extrusion was carried out using a modified Cleoren™combining adapter such as shown in FIG. 2 (a and b). The insert 14 wasprovided with seven outlets 17. The outlets width (1 through 7) (0.125in (0.32 cm) high) measured, respectively, in inches 0.125 (0.318 cm);0.313 (0.795 cm); 0.250 (0.635 cm); 0.125 (0.318 cm); 0.188 (0.478 cm);0.375 (0.953 cm); and 0.125 (0.318 cm). The middle 5 outlets were spaced3 inches (7.62 cm) apart while the end outlets were 2 inches (5.08 cm)from the next outlet. The veins 15 and 16 had a slight inward bevel atthe rounded upstream portion that tended to create a higher volumetricflow into the central openings. In each sample, the polymeric matrixmaterial was Fina 3576 (Fina Oil and Chemical Co., Deer Park, Tex.)polypropylene. The core material was based on an SEBS (styrene-ethylenebutylene-styrene) block copolymer Kraton™ G1657 (Shell Chemical Co.,Beaupre, Ohio) with varying amounts of additives listed in Table 1below, the remaining material being elastomer.

                  TABLE 1                                                         ______________________________________                                        Sample No. PAMS.sup.1   Pigment Irganox.sup.2                                 ______________________________________                                        A          --           2%      --                                            B          10%          2%      1%                                            C          15%          2%      1%                                            D          10%          2%      --                                            ______________________________________                                         .sup.1 Poly(alphamethyl)styrenes, Amoco 18210 (Amoco Oil Co., Chicago,        IL).                                                                          .sup.2 Irganox 1076 antioxidant (CibaGeigy Co., Hawthorne, NY).          

The polypropylene was extruded from a 48 mm Rheotec™ (Rheotec Extruder,Inc., Verona, N.J.) extruder into the Cloeren™ (Cloeren Co., Orange,Tex.) die. The elastomer was extruded from a 2 inch (5.1 cm), 4D ratio,screw diameter Berlyn™ extruder (Berlyn Corp., Worchestor, Mass.). Thematerial was extruded onto a 45° F. (7.2° C.) chrome casting wheelwithout a nip roll. For sample A, the Rheotec™ operated at 40 RPM with agear pump at 28 RPM and a head PSI of 1050 (74 kg/cm²). The Berlyn™operated at 5 RPM with no gear pump and a head PSI of 1800 (127 kg/cm²).The Cloeren™ operated at 360° F. (182° C.). Samples B through D operatedat the same conditions except the Rheotec™ screw RPM was 28, its gearpump RPM was 40, and head pressure was 1000 PSI(70 kg/cm²) and theBerlyn™ screw RPM was 4 with a head PSI of 1100 (77 kg/cm²).

The samples produced and their characteristics are shown in Table 2below.

                                      TABLE 2                                     __________________________________________________________________________                                                   OVER-                                    CALIPER               ELASTIC        ALL                                      (mm)      AVE. CORE/  WIDTH @        CALIPER                        SAMPLE                                                                             SKIN CORE SKIN SKIN RATIO                                                                           INITIAL                                                                            NDR   FINAL                                                                             ELASTIC                                                                            PP   RATIO                                                                             COMMENTS              __________________________________________________________________________    A    0.046 mm                                                                           0.036 mm                                                                           0.064 mm                                                                           0.65    9 mm                                                                               9 mm  9 mm                                                                             0.178 mm                                                                           0.099 mm                                                                           1.79                                                                              stretch in PP              0.018                                                                              0.112                                                                              0.020                                                                              5.87   10   37    12  0.152                                                                              0.089                                                                              1.71                                                                              elastic                    0.023                                                                              0.089                                                                              0.020                                                                              4.12   11   38    13  0.130                                                                              0.097                                                                              1.34                                                                              elastic                    0.020                                                                              0.076                                                                              0.020                                                                              3.75   17   58    21  0.137                                                                              0.102                                                                              1.35                                                                              elastic                    0.031                                                                              0.076                                                                              0.036                                                                              2.31   12   51    51  0.163                                                                              0.099                                                                              1.64                                                                              stretch in PP                                                                 and elastic           B    0.033 mm                                                                           0.056 mm                                                                           0.046 mm                                                                           1.42   14 mm                                                                              14 mm 14 mm                                                                             0.140 mm                                                                           0.089 mm                                                                           1.57                                                                              stretch in PP              0.028                                                                              0.091                                                                              0.031                                                                              2.78   15   58    20  0.145                                                                              0.097                                                                              1.50                                                                              elastic                    0.020                                                                              0.122                                                                              0.036                                                                              4.00    8   25     9  0.155                                                                              0.099                                                                              1.56                                                                              elastic                    0.028                                                                              0.097                                                                              0.023                                                                              3.80   11   35    13  5.5  3.0  1.83                                                                              elastic                    0.046                                                                              0.076                                                                              0.033                                                                              1.94   12   12    12  0.155                                                                              0.081                                                                              1.91                                                                              stretch in PP         C    0.056 mm                                                                           0.069 mm                                                                           0.036 mm                                                                           1.50   14 mm                                                                              56 mm 56 mm                                                                             0.155 mm                                                                           0.099 mm                                                                           1.56                                                                              no retraction              0.018                                                                              0.091                                                                              0.018                                                                              5.14   18   61    23  0.145                                                                              0.104                                                                              1.39                                                                              elastic                    0.023                                                                              0.089                                                                              0.031                                                                              3.33   10   32    12  0.155                                                                              0.107                                                                              1.45                                                                              elastic                    0.051                                                                              0.079                                                                              0.038                                                                              1.77   12   12    12  0.163                                                                              0.091                                                                              1.78                                                                              stretch in PP         D    0.046 mm                                                                           0.076 mm                                                                           0.051 mm                                                                           1.56   13 mm                                                                              40 mm 40 mm                                                                             0.160 mm                                                                           0.099 mm                                                                           1.62                                                                              no retraction              0.018                                                                              0.079                                                                              0.018                                                                              4.43   17   62    22  0.142                                                                              0.099                                                                              1.44                                                                              elastic                    0.025                                                                              0.089                                                                              0.025                                                                              3.40   10   32    12  0.147                                                                              0.104                                                                              1.41                                                                              elastic                    0.023                                                                              0.102                                                                              0.018                                                                              5.00   11   42    15  0.140                                                                              0.081                                                                              1.72                                                                              elastic                    0.053                                                                              0.058                                                                              0.036                                                                              1.31   11   11    11  0.160                                                                              0.081                                                                              1.97                                                                              stretch in            __________________________________________________________________________                                                            PP                

The caliper of the matrix skin and core materials was measured using anoptical microscope at the center of each elastic band. The elastic widthwas measured after casting (initial), when stretched (NDR-natural drawratio) and when recovered (final). The overall caliper was measuredusing a micrometer gauge which yielded numbers generally slightly higherthan the combined optical microscope readings for the matrix skin andcore. The PP matrix was measured adjacent to the elastic band, usually1/8 to 1/4 inches (0.32 to 0.64 cm) away. The location where the filmyielded when stretched varied. Where the core to skin ratio was lessthan 2.5 and the overall caliper ratio was over 1.5, the film eitherstretched in the polypropylene matrix field of the film or would notrecover when stretched in the Kraton™ core containing zones. It isbelieved that a higher overall caliper ratio contributes significantlyto the stretching of the polypropylene matrix field. A low core/skincaliper ratio will make the material non-recoverable if stretched in thecore containing region. All the samples in Table 1 were stretched in adirection perpendicular to M.D. (machine direction).

EXAMPLE 2

A continuous coextrusion was carried out on the apparatus described inExample 1. The screw speed of the Rheotec™ was set at 28.0 with the gearpump at 45 RPM and the head PSI at 1000. The screw speed of the Berlyn™was set at 4 RPM with a head PSI of 2000 (140 kg/cm²) . The polymermatrix was a Shell 7C50 (Shell Chemical Co., Beaupre, Ohio)polypropylene. The elastomeric core material for the four samples Athrough D corresponded to that of samples A through D, respectively, ofExample 1. The samples were tested in a manner identical to the testingperformed on samples A through D of Example 1 and the results are shownin Table 3.

                                      TABLE 3                                     __________________________________________________________________________                                                   OVER-                                    CALIPER               ELASTIC        ALL                                      (mm)      AVE. CORE/  WIDTH @        CALIPER                        SAMPLE                                                                             SKIN CORE SKIN SKIN RATIO                                                                           INITIAL                                                                            NDR   FINAL                                                                             ELASTIC                                                                            PP   RATIO                                                                             COMMENTS              __________________________________________________________________________    A    0.056 mm                                                                           0.041 mm                                                                           0.036 mm                                                                           0.89   10 mm                                                                              10 mm 10 mm                                                                             0.168 mm                                                                           0.089 mm                                                                           1.89                                                                              stretch in PP              0.018                                                                              0.089                                                                              0.020                                                                              4.67   12   40    14  0.142                                                                              0.094                                                                              1.51                                                                              elastic                    0.015                                                                              0.127                                                                              0.023                                                                              6.67   11   38    13  0.140                                                                              0.114                                                                              1.22                                                                              elastic                    0.020                                                                              0.086                                                                              0.028                                                                              3.58   18   63    24  0.145                                                                              0.109                                                                              1.33                                                                              elastic                    0.028                                                                              0.086                                                                              0.043                                                                              2.43   13   40    33  0.165                                                                              0.107                                                                              1.55                                                                              bit retraction        B    0.033 mm                                                                           0.071 mm                                                                           0.048 mm                                                                           1.75   13 mm                                                                              36 mm 28 mm                                                                             0.150 mm                                                                           0.102 mm                                                                           1.48                                                                              bit retraction             0.028                                                                              0.076                                                                              0.033                                                                              2.50   15   52    21  0.152                                                                              0.104                                                                              1.46                                                                              elastic                    0.020                                                                              0.109                                                                              0.023                                                                              5.06    8   29    10  0.163                                                                              0.104                                                                              1.56                                                                              elastic                    0.033                                                                              0.084                                                                              0.023                                                                              3.00   10   38    13  0.147                                                                              0.086                                                                              1.71                                                                              elastic                    0.058                                                                              0.061                                                                              0.036                                                                              1.30   10   10    10  0.152                                                                              0.086                                                                              1.76                                                                              stretch in PP         C    0.053 mm                                                                           0.066 mm                                                                           0.020 mm                                                                           1.79   11 mm                                                                              11 mm 11 mm                                                                             0.165 mm                                                                           0.089 mm                                                                           1.71                                                                              stretch in PP              0.028                                                                              0.097                                                                              0.0234                                                                             3.80   11   40    13  0.158                                                                              0.086                                                                              1.71                                                                              elastic                    0.020                                                                              0.114                                                                              0.018                                                                              6.00    9   30    10  0.163                                                                              0.109                                                                              1.44                                                                              elastic                    0.018                                                                              0.094                                                                              0.023                                                                              4.62   16   62    22  0.152                                                                              0.107                                                                              1.40                                                                              elastic                    0.038                                                                              0.076                                                                              0.031                                                                              2.22   13   40    27  0.163                                                                              0.102                                                                              1.50                                                                              bit retraction        D    0.053 mm                                                                           0.084 mm                                                                           0.036 mm                                                                           1.89   13 mm                                                                              43 mm 43 mm                                                                             0.165 mm                                                                           0.104 mm                                                                           1.59                                                                              no retraction              0.033                                                                              0.097                                                                              0.023                                                                              3.45   16   56    21  0.158                                                                              0.104                                                                              1.51                                                                              elastic                    0.028                                                                              0.102                                                                              0.028                                                                              3.64    9   29    10  0.163                                                                              0.104                                                                              1.56                                                                              elastic                    0.020                                                                              0.109                                                                              0.018                                                                              5.73   10   35    13  0.152                                                                              0.081                                                                              1.88                                                                              elastic                    0.061                                                                              0.058                                                                              0.041                                                                              1.15    9    9     9  0.163                                                                              0.079                                                                              2.06                                                                              stretch in            __________________________________________________________________________                                                            PP                

Similar results to that seen in Example 1 were noticed.

EXAMPLE 3

In this continuous coextrusion, the operating conditions of theapparatus were a variation of those of Example 1, Sample A, with theRheotec™ screw speed increased to 45 RPM and the head PSI increased to1050 (74 kg/cm²). The RPM of the Berlyn™ was reduced to 4, and the headPSI to 1200 (84 kg/cm²). The sample compositions A through D wereidentical to those of samples A through D of Example 1 except thatKraton™ 1107 (styrene-isoprene-styrene) was used as the elastomer.

The extrusion and stretching results for each strand are shown in Table4 (tested as in Examples 1 and 2).

                  TABLE 4                                                         ______________________________________                                                                  Ave.                                                             Caliper      Core/                                                                              Initial                                                                             Final                                                 (mm)         Skin Elastic                                                                             Elastic                                  Sample                                                                              Skin   Core    Skin Ratio                                                                              Width Width Comments                           ______________________________________                                        A     0.028  0.089   0.056                                                                              2.12 12 mm 51    no retraction                            0.015  0.079   0.025                                                                              3.88 17    19    elastic                                  0.028  0.103   0.023                                                                              4.00  9    11    elastic                                  0.023  0.107   0.025                                                                              4.42 12    13    elastic                                  0.051  0.081   0.041                                                                              1.78 11    11    stretch in PP                      B     0.036  0.066   0.031                                                                              2.00 14 mm 36    no retraction                            0.018  0.091   0.023                                                                              4.50 15    16    elastic                                  0.020  0.086   0.025                                                                              3.78 12    12    elastic                                  0.023  0.061   0.028                                                                              2.40 21    26    elastic                                  0.036  0.079   0.041                                                                              2.07 15    58    no retraction                      C     0.028  0.086   0.033                                                                              2.83 16 mm 58    no retraction                            0.015  0.091   0.018                                                                              5.54 19    24    elastic                                  0.025  0.089   0.023                                                                              3.68 11    11    elastic                                  0.020  0.084   0.031                                                                              3.30 14    16    elastic                                  0.038  0.069   0.025                                                                              2.16 14    60    no retraction                      D     0.043  0.064   0.036                                                                              1.61 14 mm 46    heat shrink                              0.028  0.107   0.031                                                                              3.65 17    23    elastic                                  0.031  0.099   0.025                                                                              3.55 15    18    elastic                                  0.020  0.119   0.015                                                                              6.71 26    33    elastic                                  0.041  0.091   0.036                                                                              2.40 16    70    no retraction                      ______________________________________                                    

As can be seen, Sample D demonstrated heat shrink characteristics at lowcore/skin ratios.

EXAMPLE 4

These continuous coextrusion samples A through D had identicalcompositions to those of samples A through D of Example 2. Properties ofthe film are shown in Table 5 (tested as above). Sample E is identicalto sample D except that the elastomer component contained 2 percentwhite pigment. Both heat and time shrink samples were noted. The shrinkmechanisms were determined at room temperature (25° C.).

                  TABLE 5                                                         ______________________________________                                                                  Ave.                                                             Caliper      Core/                                                            (mm)         Skin Elastic                                                                             Wdith                                    Sample                                                                              Skin   Core    Skin Ratio                                                                              Initial                                                                             Final Comments                           ______________________________________                                        A     0.48   0.064   0.038                                                                              1.47 12 mm 47 mm no retraction                            0.043  0.097   0.031                                                                              2.62 12    15    elastic                                  0.028  0.122   0.025                                                                              4.57  6     7    elastic                                  0.031  0.122   0.025                                                                              4.36  9    10    elastic                                  0.031  0.089   0.058                                                                              2.00 12    53    no retraction                      B     0.020  0.074   0.033                                                                              2.76  4 mm 17 mm no retraction                            0.028  0.091   0.025                                                                              3.43 15    39    time shrink                              0.025  0.107   0.028                                                                              4.00 12    13    elastic                                  0.020  0.102   0.028                                                                              4.21  8    10    elastic                                  0.018  0.125   0.018                                                                              7.00 17    20    elastic                                  0.028  0.097   0.025                                                                              3.62 16    36    time shrink                              0.023  0.069   0.028                                                                              2.70  5    19    no retraction                      C     0.025  0.076   0.028                                                                              2.86 15 mm 60    slight                                                                        retraction                               0.23   0.081   0.025                                                                              3.37 12    15    elastic                                  0.031  0.107   0.028                                                                              3.65  8    10    elastic                                  0.023  0.099   0.023                                                                              4.33 16    19    elastic                                  0.033  0.081   0.028                                                                              2.67 16    40    time shrink                        D     0.023  0.086   0.056                                                                              2.19  6 mm 15 mm slight                                                                        retraction                               0.031  0.081   0.031                                                                              2.67 16    24    time shrink                              0.018  0.137   0.023                                                                              6.75 17    21    elastic                                  0.028  0.107   0.031                                                                              3.65  9    10    elastic                                  0.031  0.099   0.028                                                                              3.39 13    14    elastic                                  0.031  0.086   0.031                                                                              2.83 16    25    time shrink                              0.036  0.056   0.031                                                                              1.69  6    20    bit retraction                     E     0.033  0.081   0.040                                                                              2.21 16 mm       slight                                                                        retraction                               0.023  0.122   0.028                                                                              4.80 13          elastic                                  0.031  0.147   0.038                                                                              4.30  9          elastic                                  0.025  0.097   0.025                                                                              3.80 17          elastic                                  0.036  0.091   0.038                                                                              2.48 16          time shrink                        ______________________________________                                    

EXAMPLE 5

The insert was provided with 1/16 inch (0.158 cm) wide, 0.125 inches(0.32 cm) high holes spaced 1/16 inch (0.158 cm) apart. The elastic corematerial was 99 percent Kraton™ 1107 and 1 percent antioxidant fed by a2 inches (5.08 cm) Berlyn™ extruder with zone temperatures varied from280° F. (138° C.) to 400° F. (204° C.) at the exit, operating at 15rotations per minute (RPM). The matrix material was a linear low densitypolyethylene, Dowlex™ 2517 (Dow Chemical Co., Rolling Meadows, Ill.) fedby a 1 inch (2.54 cm) Brabender™ (C.W. Brabender Instruments, Inc.,N.J.) extruder operating at 43 RPM and with zone temperatures rangingfrom 145° C. to 173° C., at the exit. The die and casting roll operatedat 360° F. (182° C.) and 70° F. (21° C.), respectively, with the castingroll running at 11.1 and 16.8 feet (3.4 and 5.12 m/min) for samples Aand B.

For sample C, the Berlyn™ extruder was run at the same conditions exceptthe inlet zone was set at 285° F. (141° C.), and it ran at 30 RPM. Thematrix material was changed to polypropylene (PP 3014) (Exxon ChemicalCorp., Houston, Tex.) and run at 20 RPM in the Brabender™ (zonetemperature ranging from 165° C. to 223° C.). The die and casting rollswere 400° F. and 66° F. (204° C. and 19° C.), respectively, with a rollspeed of 11.5 feet (3.5 m/min).

The dimensions of the material (mils and (mm)) obtained are shown inTable 6 below.

                  TABLE 6                                                         ______________________________________                                              Total    Thickness        Space                                         Sample                                                                              Thickness                                                                              Between,  Height Width   Between                               No.   at Core  Cores     Core   Core    Cores                                 ______________________________________                                        A      19(.48)   4(0.01) 17.2(0.44)                                                                            40(1.01)                                                                             100(2.54)                             B      10(0.25)                                                                              1.2(0.03)  9.2(0.23)                                                                            24(0.61)                                                                              92(2.34)                             C     5.6(0.14)                                                                              5.2(0.13)  4.8(0.12)                                                                           114(2.90)                                                                             116(2.95)                             ______________________________________                                    

The materials were all stretched 5:1 and allowed to relaxinstantaneously. FIG. 8 is a scanning electron micrograph of thestretched and relaxed sample B. FIGS. 6 and 7 are scanning electronmicrographs of sample C, stretched uniaxially in the cross direction andmachine direction, respectively. All the films show regular or periodicfolding when stretched in the machine direction. In samples A and B, thethickness of the matrix material between the cores 7 appeared to be dueto the low die swell of the matrix material compared to the Kraton™elastomeric core material. In all films, the matrix material completelycircumscribed the cores 7 with only the cut end of each film havingexposed core material.

In sample C, the die swell of the core and matrix materials were verysimilar and the film formed had a relatively flat profile. The corematerial in sample C was also fed at a considerably higher relativerate, to the matrix in sample C, as compared to samples A and B,resulting in a considerably larger elastomeric core region.

EXAMPLE 6

In this example, samples A through C were identical compositionally tosample C of Example 5. The Berlyn™ extruder was run at 10 RPM (zonetemperatures ranging from 370° F. (188° C.) to 420° F. (216° C.)). Thematrix was extruded from a 2 in. (5.08 cm) Rheotec™ extruder (zonetemperatures ranging from 350° F. (177° C.) to 400° F. (204° C.),operating at 61 RPM with a 400° F. gear pump at 50 RPM. The die was at400° F. (204° C.) feeding onto a 50° F. (10° C.) casting roll operatingat 54.1, 38.8 and 33.0 feet (16.5, 11.8 and 10.1 m) per minute forsamples A through C, respectively.

Sample D was run using the Brabender™ extruder for the elastic (zonetemperature range 380° to 420° F. (193° to 216° C.)) with the sameelastic. The matrix was run on the above Rheotec™ arrangement with thegear pump at 20 RPM. The matrix was 90 percent PP 8771 (Exxon ChemicalCorp.) with 10 percent blue pigment. The casting roll was 50° F. (10°C.) and ran at 21.4 feet (12.2 m) per minute.

Sample E was run the same as D, except the gear pump ran at 40 feet(12.2 m) per minute, the Brabender™ at 32 RPM and the casting roll ranat 40 feet (12.2 m) per minute.

Sample F was run the same as E except the casting roll ran at 23.3 feet(7.1 m) per minute.

Sample G was run the same as F except the casting roll ran at 21.4 feet(6.5 m) per minute, and the matrix was 50 percent polybutylene (PB 8010available from Shell Chemical Co., Beaupre, Ohio), 40 percentpolypropylene (PP 3014 available from Exxon Chemical Co., Houston, Tex.)and 10 percent blue pigment.

Sample H was run the same as F except the skin was 70 percent PP 3014,20 percent PB 8010 and 10 percent blue pigment.

The insert for this example had holes 0.125 inches (0.32 cm) high, and0.5 inches (1.27 cm) wide with 4 inches (10.16 cm) between holes.

The dimensions of the samples are set forth in Table 7 below, in mils(mm).

                  TABLE 7                                                         ______________________________________                                              Total     Thickness               Space                                 Sample                                                                              Thickness Between   Height                                                                              Width   Between                               Number                                                                              at Core   Cores     Core  Core    Cores                                 ______________________________________                                        A     3.5 (0.089)                                                                             3.0 (0.076)                                                                             --    1.4 (0.036)                                                                           2.0                                                                           (0.051)                               B     4.3 (0.11)                                                                              4.2 (0.11)                                                                              --    1.5 (0.038)                                                                           2.0                                                                           (0.051)                               C     5.1 (0.13)                                                                              5.1 (0.13)                                                                              --    1.4 (0.036)                                                                           2.0                                                                           (0.051)                               D     8.0 (0.18)                                                                              7.0 (0.18)                                                                              --    1.1 (0.028)                                                                           2.4                                                                           (0.061)                               E     4.2 (0.11)                                                                              3.4 (0.088)                                                                             --    1.0 (0.025)                                                                           2.1                                                                           (0.053)                               F     4.3 (0.11)                                                                              3.6 (0.091)                                                                             --    0.9 (0.023)                                                                           2.1                                                                           (0.053)                               G     3.7 (0.094)                                                                             3.9 (0.099)                                                                             --    1.3 (0.033)                                                                           2.0                                                                           (0.051)                               H     5.5 (0.014)                                                                             5.0 (0.127)                                                                             --    1.0 (0.025)                                                                           2.1                                                                           (0.053)                               ______________________________________                                    

These samples were all stretched 5:1 in the machine direction andrelaxed instantaneously.

EXAMPLES 7 AND 8

Samples B and C of Example 5 were coated with adhesive and wereidentified as Examples 7 and 8, respectively. Example 7 was coated witha hot-melt coatable, pressure-sensitive adhesive comprising a tackifiedsynthetic block copolymer. Example 8 was laminated to a 37.5 mil thickacrylate adhesive (3M 9671SL). Both tapes were formed by applying theadhesive prior to stretching the backing. Tape 7 was adhered to itselfand a glass plate after stretching in the machine direction. Tape 8 wasalso adhered to itself and a glass plate after stretching in the machineand cross directions. All the tapes were stretched uniaxially at a 5:1draw ratio. The tapes were peel tested at 90 degree and 180 degree peelangles, after adhering with a 5 lb. rolldown (1 minute dwell), at a peelrate of 90 inches/min (5 second average value). The results are shown inTable 8 below in gm/inches. "Flat" indicates the film prior tostretching and "Stretched" indicates the film after stretching andrecovery. Tapes 7 and 8 (MD) tore in the machine direction.

                  TABLE 8                                                         ______________________________________                                        Example       7          8 (MD)  8 (CD)                                       ______________________________________                                        Adhesion to Glass                                                             1800 Flat     1,690      336     540                                          1800 Stretched                                                                              561        312     317                                           900 Flat     544        333     463                                           900 Stretched                                                                              264        168     213                                          Adhesion to Backside                                                           180° Flat                                                                           360        207     309                                           180° Stretched                                                                      456        212     125                                           90° Flat                                                                            286        208     266                                           90° Stretched                                                                       140        120     191                                          ______________________________________                                    

For Examples 7 and 8 (MD), the 180 degree Stretched Adhesion to Backsidewas higher than to the Flat Adhesion to Backside peel indicating thatthere was likely inter-penetration of the macrostructure folds of theadhesive and the macrostructure folds of the backside.

The various modifications and alterations of this invention will beapparent to those skilled in the art without departing from the scopeand spirit of this invention, and this invention should not berestricted to that set forth herein for illustrative purposes.

We claim:
 1. A continuous nonwoven film laminate comprising at least onefibrous nonwoven layer laminated to an elastic film layer comprising atleast one discrete elastomeric core containing region capable of elasticelongation and a matrix of thermoplastic polymeric material, whichpolymeric matrix material is less elastic than the elastomeric corematerial, said matrix material providing at least two nonelastic filmregions comprising nonelastic matrix material wherein said film has beenstretched in the transverse direction past the inelastic deformationlimit of the matrix material around said at least one elastomeric coreforming at least one elastic region which laminate is extensible in thetransverse direction and nonextensible in the longitudinal direction. 2.The continuous nonwoven film laminate of claim 1 wherein the at leastone elastomeric core comprises an extrudable polymer and said matrixmaterial is a thermoplastic polymer.
 3. The continuous nonwoven filmlaminate of claim 1 wherein the fibrous nonwoven layer is extended inthe elastic region of the film and nonextended in the nonelastic regionof the film wherein the laminate is extensible and elastic in thetransverse direction.
 4. The continuous nonwoven film laminate of claim1 wherein the fibrous nonwoven layer is nonextended in the elasticregion of the film.
 5. The continuous nonwoven film laminate of claim 4wherein the laminate is extensible and elastic in the transversedirection.
 6. The continuous nonwoven film laminate of claim 4 whereinthe laminate is extensible and nonelastic in the transverse directionand further wherein when said laminate is stretched in the transversedirection the laminate will stretch in the elastic region of the filmand recover to form an laminate that is extensible and elastic in thetransverse direction.
 7. The continuous nonwoven film laminate of claim1 wherein the fibrous nonwoven layer is heat or sonicly bonded to thefilm layer.
 8. The continuous nonwoven film laminate of claim 1 whereinthe fibrous nonwoven layer is adhesively bonded to the film layer. 9.The continuous nonwoven film laminate of claim 1 wherein the fibrousnonwoven layer is extrusion laminated to the film layer.